Basic Wind Velocity (v_b): Section 4.2

Basic wind velocity (v_b) is defined according to the following equation:

v_{b} = c_{d i r} c_{s e a s o n} c_{p r o b} v_{b, 0}

(4.1)

where

c_dir	=	direction factor (NA.2.6)
c_season	=	season factor (NA.2.7)
c_prob	=	probability factor
v_b,0	=	fundamental value of the basic wind velocity (m/s).

Section NA.2.4 defines v_b,0 = v_b,mapc_alt in which altitude factor c_alt is defined in Equations (NA.2a) and (NA.2b).

c_{a l t} = 1 + 0.001 A f o r z \leq 10 m

(NA.2a)

c_{a l t} = 1 + 0.001 A {(\frac{10}{z})}^{0.2} f o r z > 10 m

(NA.2b)

The preceeding equations are not implemented. Instead, it is expected that you directly provide v_b,0. Also note that section NA.2.5 says Eq. (NA.2a) can be conservatively used for any building height.

Note: c_dir can be different for X and Y directions.

c_dir, c_season, c_prob, and v_b,0 are user-defined values.

Basic Wind Velocity (vb): Section 4.2

Basic Wind Velocity (v_b): Section 4.2